This invention generally pertains to filtering assemblies. More specifically, the present invention relates to a selectively openable filtering assembly.
The invention is particularly applicable to a remotely openable filter member which treats contaminated air passing therethrough. However,. it will be appreciated by those skilled in the art that the invention has broader applications and may be useful also in a means for remotely opening a filter in other filtering environments where a filter is used to treat gases or liquids. More broadly, the means for remotely opening a package may find many uses outside the filtering environment as well.
Charcoal filters are typically used in breathing apparatus for fire fighters, miners, soldiers in the field, etc. Because the breathing apparatus is, typically, only used in emergency situations, it may be stored on the shelf for long periods of time. When it comes time to use the breathing apparatus, it may be found that the charcoal granules constituting the filtering medium have been rendered ineffective due to an extended period of exposure to the atmosphere. Typically, moisture and other constituents in the atmosphere will react adversely with the activated charcoal in the filter, causing the charcoal granules in the filter to lose their desirable adsorption properties.
In many different types of industrial environments, it is necessary for a worker to wear some type of respirator to avoid breathing the contaminated air of the work environment. To this end, different types of respirators have been devised for providing the worker with uncontaminated breathing air. For this type of respirator, generally no protection is necessary for the air cleaning element since it is continually in use during the workday.
Even for a breathing apparatus which is used only intermittently, there have been designed filter elements which are protected from the environment by a cover which is manually removable such as by pulling a pull tab, a corner, a string, or the like. However, under certain circumstances, the filtration element or filter unit of a breathing device or respirator is .not accessible for the removal of such a covering element thereon absent the disassembly of the respirator in question. This is particularly the case in respirators which have a built-in filtering unit or filter member. In an emergency situation, there may not be time to disassemble the respirator apparatus so as to have access to the filter unit itself in order that any protective covering on the filter unit can be removed thereby allowing air to flow through the filter.
Another environment in which filter units are generally inaccessible is in a survival shelter adapted for use as a place of refuge during warfare, industrial accidents, earthquakes, terrorism, or sabotage and the like. Such conventional shelters are provided with various filtration devices for filtering the air of the environment such as the so called "NBC" (nuclear, biological, chemical) filtration devices. These devices generally house a filtration cartridge, which may be an activated charcoal cartridge or the like, for filtering the air which is allowed to enter the shelter. The filter cartridge is generally inaccessible without a disassembly of the entire filter mechanism. In an emergency, however, there will generally not be enough time to disassemble the filtration mechanism to have access to the filter unit itself in order that any protective covering on the filter unit can be removed.
Additionally, it may be advantageous in certain industrial environments, such as petrochemical plants, nuclear power stations, ammunition manufacturing plants, various types of mines and the like, whether for the supply of air or other fluids, to provide a filter assembly which is protected by a cover from communication with its environment until needed and in which there is provided a remotely activated means for quickly opening the cover, in order to expose the filter medium to communication with fluids in the environment, without needing direct access to the filter assembly.
Accordingly, it has been considered desirable to develop a new and improved means for selectively opening a package such as a filter assembly by remote control and a heat severing means for a package cover material which would overcome the foregoing difficulties and others and meet the above-stated needs while providing better and more advantageous overall results.